The brown dwarf: Why this mysterious celestial body matters

SIMP-0136 is a strange celestial object somewhere between a planet and a star. Using the new space telescope, researchers have now spotted a curious phenomenon on this so-called brown dwarf. Dublin (dpa) – Northern lights, or auroras, are not exclusive to Earth. Astronomers have already detected this phenomenon on most planets and many moons in our solar system. Now, an international research team has reported the discovery of similar luminous displays on the brown dwarf SIMP-0136, located 20 light-years away. These auroras heat the upper atmosphere of the celestial object by 250 degrees Celsius, according to findings published in the journal Astronomy & Astrophysics. "These are some of the most precise measurements of the atmosphere of any extra-solar object to date, and the first time that changes in the atmospheric properties have been directly measured," said Evert Nasedkin of Trinity College Dublin, Ireland. The researcher noted that the James Webb Space Telescope enables the detection of temperature changes as small as five degrees Celsius over such vast distances. SIMP-0136 rotates once every 2.4 hours, during which its brightness and temperature fluctuate. What is SIMP-0136? SIMP-0136 is a brown dwarf, a celestial object that's somewhere between a planet and a star. While planets shine by reflecting the light of their central star, stars like our Sun generate light and heat through nuclear fusion — the merging of hydrogen into helium. Brown dwarfs, often referred to as "failed stars," have masses between 12 and 75 times that of Jupiter. However, the pressure and temperature in their cores are insufficient for standard hydrogen fusion. Instead, they fuse the rarer "heavy hydrogen" isotope deuterium into helium, producing only minimal heat. SIMP-0136, for instance, has a surface temperature of around 1,500 degrees Celsius. Surprisingly, researchers discovered that its upper atmosphere is 250 degrees hotter, suggesting that it's getting external energy from auroras. Auroras occur when electrically charged particles, such as electrons and atomic nuclei, enter a celestial object's atmosphere along its magnetic field. Smallest known object with auroras beyond the solar system On Earth, auroras are caused by charged particles from the Sun. In the case of SIMP-0136, however, the particles originate from interstellar space, as the brown dwarf is a solitary object that does not orbit a star. Astronomers had previously detected auroras on two other brown dwarfs, but these were significantly more massive than SIMP-0136. With a mass of just 15 times that of Jupiter, SIMP-0136 is the smallest known celestial object beyond our solar system to exhibit auroras. This makes it particularly intriguing for astronomers. SIMP-0136 is close to the mass threshold of 12 Jupiter masses, which separates planets from brown dwarfs. As such, it serves as "an ideal analogue for the directly imaged exoplanet population," Nasedkin and his colleagues write, particularly for studying their atmospheres. Until now, astronomers believed that atmospheric temperature changes on such objects were primarily influenced by cloud cover. However, SIMP-0136 demonstrates that auroras can have a previously underestimated impact on atmospheric temperatures. The following information is not intended for publication dpa fm zlw yyzz n1 waw coh

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